On Thu, 5 Aug 2021 09:27:15 -0400 Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote: > On transition from 2->1 callees, we should be comparing .data rather > than .func, because the same callback can be registered twice with > different data, and what we care about here is that the data of array > element 0 is unchanged to skip rcu sync. > > Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@xxxxxxxxx/ FYI, You only need to show one Fixes. > Fixes: d25e37d89dd2 ("tracepoint: Optimize using static_call()") The above is fixed by the one below. Which means all the stable kernels that have the above, will also have the below, and thus the above is just redundant. > Fixes: 547305a64632 ("tracepoint: Fix out of sync data passing by static caller") The above is what the patch actually fixes. > Fixes: 352384d5c84e ("tracepoints: Update static_call before tp_funcs when adding a tracepoint") How does this patch fix the above? Perhaps the above did not go enough to fix the issue, but it's unrelated. I'll remove the first and last Fixes tag. > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > Cc: Stefan Metzmacher <metze@xxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.10+ The "# 5.10+" is now obsolete, and not needed. The Fixes tag is used to determine where this gets backported to. Other than that. This patch looks good. -- Steve > --- > kernel/tracepoint.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c > index fc32821f8240..133b6454b287 100644 > --- a/kernel/tracepoint.c > +++ b/kernel/tracepoint.c > @@ -338,7 +338,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, > } else { > rcu_assign_pointer(tp->funcs, tp_funcs); > tracepoint_update_call(tp, tp_funcs, > - tp_funcs[0].func != old[0].func); > + tp_funcs[0].data != old[0].data); > } > release_probes(old); > return 0;
